The news that China is planning to build three more dams on the Yarlung Tshangpo (as Siang, the main tributary of the Brahmaputra is known in Tibet) has lead to a fresh interest in the issue.
Before I elaborate, here are some facts: out of Brahmaputra's total catchment area of 5,80,000 sq
km, China has 50.5%, India 33.6%, the rest almost equally in Bhutan and Bangladesh. Out of 2,880 km length of the river, 1,625 km flows in Tibet, 918 km in India and 337 km in Bangladesh. A 510 MW dam called Zangmu has been under construction since November 2010 and China has built six other projects on the tributaries of the Tsangpo. It has now declared that it is going to build 640 MW dams at Dagu, Jiexu (7 km downstream of Dagu and 11 km upstream of Zangmu) and 320 MW at Jiacha. Worryingly Xinhua, the official Chinese news agency, said the $1.2 billion Zangmu project "can also be used for flood control and irrigation".

For a project to be useful for irrigation and flood control, it needs to store and divert water. The Zangmu and the other hydropower projects will have adverse downstream impacts. Considering China's past record, any assurances from them of being responsible towards downstream countries do not hold water.

There is a tendency among supporters of dams to say that run-of-the-river (RoR) projects, like the one that is being built at Zangmu, are environment friendly. But the truth is such projects have several adverse impacts: submergence, displacement, deforestation and destruction of aquatic and terrestrial biodiversity, to name a few.

The Chinese projects on the Tsangpo will have significant impact on India: changed water and silt flow patterns, increased flood and erosion capacity of river and adverse impact on the biodiversity in the river that has close links with the livelihoods of lakhs.

India has been less than firm with China on these issues. The government informed Parliament in the past that China has not disclosed the reasons for destructive floods in Himachal Pradesh in August 2000 and in Arunachal Pradesh in June 2000, even though floods in both cases originated from China. In fact, to say the truth, India's treatment of impacts of its own such projects on downstream communities or those of our neighbours has been far from inspiring.

One mechanism to tackle China could have been the United Nations Convention on Non-Navigation Use of Water. But India did a disservice to its cause by abstaining from voting in favour during the debate for the convention and not ratifying it later. The only plausible course for India now is to push for a water-sharing treaty with China.

Himanshu Thakkar is with the South Asia Network on Dams, Rivers & PeopleThe views expressed by the author are personal